Complete all test chambers in the Mass and Velocity co-op course
Complete all test chambers in the Team Building co-op course
Celebrate your cooperative calibration success
Survive the manual override
Reunite with GLaDOS
Complete the first Thermal Discouragement Beam test
Complete the first Hard Light Bridge test
Make a break for it
Press the button!
Carry science forward
Master the Repulsion Gel
Master the Propulsion Gel
Complete the first Conversion Gel test
Master the Excursion Funnel
Do the same test twice
This is that part
That just happened
Place a cube on a button without touching the cube
Complete Test Chamber 10 in 70 seconds
Show that pit who's boss
Break the rules in Test Chamber 07
Use an Aerial Faith Plate to launch a turret
Find the hidden signal in one of the Rat Man's dens
Take GLaDOS' escape advice
Stand in a defective turret detector
Save a turret from redemption
Discover the missing experiment
Examine all the vitrified test chamber doors
Find a hidden portrait
Refuse to solve the first test in Chapter 8
Complete all test chambers in the Hard-Light Surfaces co-op course
Complete all test chambers in the Excursion Funnels co-op course
Complete all test chambers in all courses of co-op
Never lose a cube in Chamber 6 of the Mass and Velocity co-op course
Perform all 8 gestures of your own volition in co-op
Dance in front of a turret blocked by a hard light bridge in co-op
Drop your co-op partner in goo while they are gesturing by removing the bridge under them
Place a portal under your co-op partner while they are gesturing
Perform 2 aerial gestures before touching the ground in co-op
Complete Chamber 3 in the Hard-Light Surfaces co-op course using only 5 total portal placements
Complete Course 4 with neither you nor your co-op partner dying
Taunt GLaDOS in front of a camera in each of the five co-op courses
Win 3 co-op games of rock-paper-scissors in a row
Catch a blue-painted box before it touches the ground
Break 11 test chamber monitors
Find the hidden companion cube in co-op test chamber
After completing co-op, complete Calibration Course online with a friend who hasn’t played before
Enter 4 different portals without touching the ground in co-op
Solve 3 co-op chambers in the Mass and Velocity course in under 60 seconds each
While playing co-op, hug 3 different people on your friends list
Never lose a cube in Chamber 6 of the Mobility Gels co-op course
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